Sharp dental instruments called curettes (alternate spelling: curets) are used during the scaling or planing of human teeth during hygienic cleaning. These curettes are typically made of stainless steel and require frequent resharpening. This is typically done on a conventional sharpening stone. Such stones may be rectangular slabs or wedges. They may have rounded edges or be straight or tapered cylinders for the sharpening of interior radii. Kits with a variety of stone shapes are sold. The flat surface of the stone may also contain V-grooves for the simultaneous sharpening of two cutting edges. Many types of fixtures have been developed to achieve a more consistent finish when performing manual sharpening. Many other powered sharpening systems have also been developed.
To prevent cross-contamination of patients, all dental instruments are sterilized between patients by steam autoclave (generally the only sterilization means available in a dental office). The powered sharpening systems are not sterilizable. Therefore, after sharpening, the curette must be resterilized. Since this takes at least 10–20 minutes, the powered sharpening systems may only be used between patients, not during treatment of a patient. This also applies to many of the manual sharpening systems.
In contrast, hand-held sharpening stones are typically sterilizable. If they are sterile, this means they may be used before or after the curette is sterilized. This allows resharpening of the curette either before a patient, or during a treatment when the curette becomes dull. However, when scaling, the hygienist or dentist (hereinafter, “hygienist”) generally holds a dental mirror in one hand and the curette in the other. Sharpening a curette with a hand-held stone requires the hygienist to free their other hand. The hygienist must also turn away from the patient to retrieve the stone from the instrument tray, and then replace it after the sharpening. These steps waste time and motion, and inhibit the user from sharpening their tools at the optimum intervals. Working with dull tools increases treatment time, contributes to hygienist fatigue, results in inferior cleaning of the teeth, and may increase the risk of unintended damage to the mouth due to greater forces required for difficult planing.